Last time I was at a place with loud window-shaking (literally) bass, that has vibrations that you can feel in your clothing, well I think that is more (physically) potentially damaging than the high frequencies.
A shrieking sound or high-pitched sibilance makes you turn the volume down straight away and doesn't sound nice, but some people like heavy muddy bass in IEM's and headphones (I don't), and when listening to the JVC FXC51's (without EQ) at the same volume I'd listen to an IEM like the EX600, I thought after only 15 minutes or so the FXC51 would have me fatigued, whereas a bass-light IEM or headphone I can listen to for much longer with no issue.
I have a funny sensation in my left ear sometimes like it's less sensitive to low frequencies but I tested my hearing (basic stuff, online) and I can still hear from 17Hz to 19kHz so I guess nothing is wrong, maybe it's just that "air block" thing you have when you have a cold? It's annoying.